Mix together ground beef, breadcrumbs, onion soup mix and milk
Mix well
Form into 8 patties
Slice onion
Dredge patties, one at a time, in flour
Fry patties in skillet one at a time, until brown on both sides
Place the patties in the crock pot, layering them as necessary
Spread sliced onions over the patties
Spread sliced mushrooms over the patties
In a medium sized bowl mix together soup, bouillon, and water
Pour soup mixture over top of patties and cover with lid
Cook in slow-cooker on low for 4 hours
Serve